Electrical indicating system



Aug. 5, 1958 H. I. BAKER 2,346,531

auzc-mrcu. INDICATING sYs'rsu Filed Nov. 7, 1956 2 Sheets-Sheet 1 4INVENTOR. J4 #477? I Z4167- H. I. BAKER 2,846,531

suzcmxw. mmcmuc sYs'rEu Aug. 5, 1958 Filed Nov. 7, 1956 a Sheets-Sheet 24f I I I WW1 I I INVENTOIQ. #477] I ,Zai r.

United States Patent This invention relates to telemetering systems and,more particularly, to condition indicating and signaling apparatus.

The principles of the invention are representatively embodied in anapparatus for providing a continuous or an effectively continuousindication of a remote condition, such as the temperature of a body, andfor signaling the attainment of a preselected critical value of thatcondition, such as the attainment of a preselected temperaature as theresult of heating or cooling of the body.

Objects of the invention are to improve indicating and signalingdevices, and to reduce their cost of manufacture and maintenance.

Another object of the invention is to provide improved means forpivotally supporting a manually settable point-' er and an indicatingpointer upon separate pivots.

Another object of this invention is to provide an improved means forsupporting one electrical contact in a manually adjustable positionrelative to a second electrical contact the position of which isdetermined by an electroresponsive mechanism The manner of accomplishingthe foregoing objects, and other objects and features of the invention,will become apparent from the following detailed description ofembodiments of the invention when read with reference to theaccompanying drawings, in which:

Figure 1 is a schematic representation of a control system including anapparatus embodying the principles of the present invention;

Figure 2 is a front elevational view, partially cut away, of one form ofapparatus embodying the principles of the present inventional andsuitable for inclusion in the system of Figure 1;

Figure 3 is a sectional view taken substantially along the line 3-3 ofFigure 2; I

Figure 4 is a front elevational view, partially cut away, of anotherform of apparatus embodying the principles of the present invention andsuitable for inclusion in the system of Figure 1;

Figure 5 is a sectional view taken substantially along the line 55 ofFigure 4;

Figure 6 is a sectional view taken substantially along the line 66 ofFigure 4; and

Figure 7 is a sectional view taken substantially along the line 7--7 ofFigure 6. In the control system representatively illustrated in Figurelot the drawings, a voltage regulating device 10 is employed to applyenergy from a source 12 to a controlling circuit including an indicatingand signaling instrument 14 and a sensing unit 16. When a preselectedcritical condition obtains, the instrument 14 completes a circuit forenergizing an output relay 18 which is adapted to control a loadcircuit.

The source 12 is connectable, upon the closure of switch 20, across theprimary winding of transformer 22 so as to develop a voltage across thesecondary winding ofthat transformer, that is, between conductor 24 andthe system ground. It will be appreciated that a metallic return circuitmay be employed if desired and that other sources of input voltage maybe employed, including a battery or-other direct current source or analternating curent source without the interposition of a transformer.

Conductor is connected to a fixed or adjustably fixed electrical contact26 adapted to mate with a contact 28 carried by a cantilever-mountedpolymetallic element 30. A heater winding 32 is disposed in heattransfer relationship with element 30, one end of the winding beingelectrically connected to the element 30 and the other end' of thewinding being connected to the system ground. By virtue of theseconnections, heater winding 32 is energized when contacts 26 and 28 areclosed, the resultant elevation of the temperature of polymetallicelement 30 producing a deflection of that element in a direction toseparate contact 28 from contact 26, interrupting the energization ofthe heater 32 and permitting the polymetallic strip 30 to cool until thecontacts 26 and 28 are again brought into engagement. The device 10therefore functions as an electro-thermal self-interrupter and willoperate, in the manner disclosed in Patent 2,762,997, granted September11, 1956, to Leonard Boddy, to maintain a pulsating voltage ofsubstantially constant average magnitude across its heater winding 32and hence between polymetallic element 30 and the system ground.

The pulsating, constant-average-magnitude voltage appearing betweenconductor 34, connected to polymetallic element 30, and the systemground is applied across a series indicating or gauging circuit whichmay be traced from conductor 34, input terminal 11, heater winding 36, aconstituent element of instrument 14, input terminal 12, conductor 39,through sensing device 16, and to the system ground. Sensing device 16is representatively illustrated in the form of a probe suitable forinsertion, for example, in a piece of meat to sense its internaltemperature. Senser 16 is shown to comprise a resistor 41 having a hightemperature coefficient of resistance electrically insulated from theprobe casing but in good thermal contact with the tip of that casing. Intheillustrated arrangement, it is assumed that resistor 41 has a highnegative temperature coeflicient of resistance.

Heater winding 36 is disposed in heat transfer relationship with apolymetallic leg portion 38 supported essentially as a cantilever, aswill be seen. Leg portion 38 has an end projection 40 to which anelectrical contact 42 is secured and is connected to grounded outputterminal 01 so that contact 42 is maintained at the system groundpotential. Polymetallic leg portion 38 is also adapted to drive, in amanner more clearly disclosed in the structural views of Figures 2-7, anindicating pointer 44 rotatable about a pivotal axis 46 and adapted tocooperate with a scale 48. r

The orientation of the constituent metallic elements of the polymetallicleg 38 is selected in the light of the direction of the temperaturecoefficient of resistance of senser resistor 41 so that increasingsensed temperatures will result in the deflection of the indicatingpointer 44 in a direction along the scale 48 to produce acorrespondingly increased temperature indication. In the representativearrangement, with a negative temperature coefficient of resistanceresistor 41, increasing sensed temperatures will result in increasedcurrent throughwinding 36 and increased heating of leg 38 to produce anincreasing deflection of that leg. This increasing deflection is in adirection to deflect pointer 44 in a. clockwise direction, assumingscale 48 to be calibrated in increasing temperatures from left to right.

This same motion of polymetallic leg 38 serves to move contact 42 to theright in the view of Figure 1 towards its mating contact 50. Theposition of contact 50 is preferably manually adjustable to permitsetting of the critical value at which the output function will beperformed, and means in the form of a setting pointer 52 are preferablyprovided for providing, in cooperation with scale 48 or another scale,an indication of that setting. While the arrangements illustrated in thestructural views are preferred, contact 50 is shown for diagrammaticclarity, mounted upon setting pointer 52, with that shaft beingpivotally mounted upon shaft 54. The rotational positioning of shaft 54both sets the position of pointer 52 and adjusts the position of contact50 in its spacing from contact 42.

Electrical contact 50 is connected to output terminal 02 which, in turn,is connected to the voltage at conductor 24 through the winding ofoutput relay 18. When the sensed temperature has in the disclosedarrangement risen to the selected value, contact 42' will engage contact50 to complete a circuit from ground, terminal 01, polymetallic element38, contacts 42 and 50, terminal 02, winding of relay 18 and toconductor 24, operating relay 18 to close contacts 56 to connect theload 58 across a source of energy 60. Load 58 may be a visible signalsuch as a lamp, an audible signal such as a hell or buzzer, or acontrolling device. It is, of course, possible to employ normally closedcontacts rather than normally open contacts 56 as elements of relay 18and to connect the heater (which is to supply heat to the body thetemperature of which is sensed by senser 16) as the load 58, althoughthe device illustrated is intended primarily, and best serves, as anindicating and signaling mechanism.

The indicator mechanism 14 may assume either the form shown in Figures 2and 3 or the form shown in Figures 47.

The unit disclosed in Figures 2 and 3 of the drawings comprises a faceplate 70, bearing scale indicia 48 and surmounting and secured to a case72. The motivating electroresponsive element including active legportion 38 is a generally U-shaped polymetallic element also including aback or compensating leg 74, one end of which is joined to one end ofactive leg 38 by a flanged crosspiece 76. The other end of the ambienttemperature leg 74 is riveted or otherwise secured to an upstandingflange 77 upon a calibrating arm 78, the other end of which is securedto the case 72 in a manner so that the arm 78 resists rotation but isrotatable to adjust the instrument, upon the application of suitableforce. The illustrated aflixing means comprises a rivet designated 01since it is the means by which the polymetallic element is electricallyconnected to the case, it being assumed that the case is connected tothe system ground.

The heater winding 36, disposed in heat transfer relationship with theactive polymetallic leg portion 38 is connected to input terminals 11and 12. The free end of leg portion 38 is bent reversely to define theprojection 40 which supports the active electrical contact 42, the anglebetween the leg portion 38 and the projection 40 defining a knee ornotch serving a function to be described.

A second calibrating arm 80 is frictionally rotatably mounted upon thecasing 72 by a rivet 82, and a flexible calibrating spring arm 84 isriveted or otherwise secured to an upstanding flange 86 on arm 80. Theend 88 of spring arm 84 is bent to define a knee or notch positionableproximate the knee or notch defined by the junction of polymetallicstrip 38 and projection 40 and serving, in a manner to be described, asthe pivotal axis 46 above discussed with reference to Figure l.

A generally frame-shaped sheet metal link 90 is supported by elements 38and 84, the projection 40 of the polymetallic element 38 and the endportion 88 of the calibrating spring arm 84 passing through the centralaperture of the frame and the edges of the frame engaging the notches orknees on those elements. Link 90 is provided with an integral extension92 which supports and is illustratively integral with the indicatingpointer 44. Heating of the polymetallic active leg portion 38 by heater36 will cause the projection 40 to be moved generally to the right inthe view of Figure 2 to tilt the link 90 about pivotal axis 46 andthereby to rotate indicating pointer 44 in a clockwise direction.

This movement of the free end of polymetallic element 38 and ofprojection 40 will cause contact 42 to be moved generally to the righttowards contact 50. Contact 50 is supported upon an upstanding legportion 93 secured intermediate the ends of a supporting arm 94 which ispivotally secured to but electrically insulated from the case 72 bymeans including terminal screw 02. The remote end of arm 94 is providedwith teeth defining a rack or sector 96. Sector 96 is adapted to engagethe teeth of a pinion gear 98 carried by or formed on shaft or arbor 54.Shaft 54 is rotatably supported by plates 100 and 102 depending fromcase 72 and carries a manual adjusting knob 104. The setting pointer 52is secured to and rotatable with the knob 104 and the shaft 54.

As knob 104 and shaft 54 are rotated, the position of setting pointer 52with respect to the indicia 48 is changed and arm 94 is rotated aboutits pivot to shift the position of contact 50 relative to the activecontact 42. The more the knob 104 is rotated in a clockwise directionand the higher the setting of pointer 52 (assuming that the indicia 48reflect increasing temperatures from left to right), the further contact50 is spaced from the contact 42 under initial temperature conditionsand the higher the sensed temperature must become before contact 42 willengage contact 50 to produce the output indication. The ratio of pinionto sector size is selected to provide the same motional relation betweenthe setting pointer 52 and the adjustable contact 50 as that whichexists between the indicating pointer 44 and the active contact 42 inorder that the contacts will close when the indicating pointer 44reaches the indicated temperature at which the setting pointer 52 isset.

It will be observed that the pivotal axis 46 and the longitudinal axisof shaft 54 are in approximately vertical alignment so that whatever therange of travel, the fact that the pointers 44 and 52 are not pivotingabout the same axis will not be apparent to the observer. Thearrangement illustrated in Figures 4-7, however, permits theestablishment of substantially coaxial pivots for the two pointers. Thestructure in this modified, and presently preferred, arrangement issimilar to that previously described and corresponding parts aredesignated with the same reference characters sutfixed by a prime.

The difl'erences between the structure of Figures 4-7 and the structurepreviously described pertain primarily to the location and supporting ofthe arbor 54 and the supporting and adjusting of the passive contact 50,although there are other minor changes including a repositioning of theactive contact 42' upon the projection 40', as may best be seen inFigure 7 of the drawings.

The passive contact 50 is mounted upon arm 94 which, in this case, isflexible, with contact adjustment being accomplished by flexing the arm94'. The upper end of arm 94' is rigidly secured to the case 72 in themanner best shown in Figure 5. Arm 94' is formed with an integralportion which is bent laterally to define a mounting flange 112. Flange112 is interposed a washer 114 and an insulating washer 116, the latterof which abuts the inner face of casing 72'. An insulating washer 118having a projecting shoulder is mounted on the reverse side of casing72', with its shoulder seated within an aperture in that casing.Terminal O2 is disposed between outer face of insulator 118 and a springwasher 120. The stack is maintained in its assembled relationship by arivet 122.

Near its free cnd, and representatively adjacent the point of attachmentof the passive contact 50' to the arm 94', arm 94' is provided with aprojection 124 (Fig. 7) carrying an upstanding V-shaped end portion 126serving, as will be seen, as a cam follower.

Shaft 54' is rotatably supported by a bridge 128 (Fig. 6) secured in anysuitable fashion to the casing 72. A spring washer 130, engaging theinner face of bridge 128, a cam 132, a washer 134 and the settablepointer 52 are mounted upon a portion of the shaft 54, the end of theshaft being headed over to maintain these elements in their shownrelationship. It will be observed that the position of bridge 128 isselected so that the longitudinal axis of the shaft 54"substantiallycoincides with the pivotal axis- 46' of the indicating pointer 44, thatis, so that the pivotal axis of the two pointers 44' and 52'substantially coincide even though those pointers have different pivotelements.

Cam follower 126 engages the edge of cam 132 so that upon rotation ofshaft 54 the position of cam follower 126 will be changed, deflectingcontact spring arm 94' and changing the position of passive contact 50'relative to active contact 42'. The shape of the cam surface 132 isselected to establish the correct relationship between the position ofpointer 52 and the indicia 48' with reference to the temperature atwhich the contacts 42' and 50' will be closed to produce the outputfunction.

While it will be apparent that the embodiments of the invention hereindisclosed are well calculated to fulfill the objects of the invention,it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the properscope or fair meaning of the subjoined claims.

What is claimed is:

1. A manually adjustable indicating device comprising a mounting plate,an indicating pointer movable to indicate the magnitude of a condition,a first electrical contact, electroresponsive means supported upon saidmounting plate for moving said pointer and for moving said firstelectrical contact relative to said mounting plate, an arm, supportingmeans for supporting said arm at one end on said mounting plate, asecond electrical contact secured to a portion of said arm and matablewith said first electrical contact, a manually rotatable shaft supportedfor rotation relative to said mounting plate and about an axis locatedupon the opposite side of a line through said contacts from saidsupported one end of said arm, and means including said shaft and saidarm for varying the position of said second electrical contact relativeto said mounting plate and hence relative to said first electricalcontact.

2. Amanually adjustable indicating device comprising a mounting plate,first and second matable electrical contacts, electroresponsive meanssupported upon said mounting plate for moving said first electricalcontact relative to said mounting plate, an arm, supporting means forsupporting said arm at one end on said mounting plate, means securingsaid second electrical contact to said arm at a portion thereof remotefrom said one end, a manually rotatable shaft supported for rotationrelative to said mounting plate and about an axis located upon theopposite side of a line through said contacts from said supported oneend of said arm, and means respon sive to rotation of said shaft formoving said portion of said arm relative to said mounting platecomprising driving means on said shaft and driven means on said amengageable with said driving means.

3. A manually adjustable indicating device comprising a mounting plate,first and second matable electrical contacts, electroresponsive meanssupported upon said mounting plate for moving said first electricalcontact relative to said mounting plate, an arm supported at one end bysaid mounting plate, means securing said second electrical contact tosaid arm at a portion thereof remote from said one end, a manuallyrotatable shaft supported for rotation relative to said mounting plate,and means responsive to rotation of said shaft for moving said portionof said arm relative to said mounting plate comprising a gear on saidshaft and a rack on said arm engageable with said gear. I

4. A manually adjustable indicating device comprising a mounting plate,first and second matable electrical contacts, electroresponsive meanssupported upon said mounting plate for moving said first electricalcontact relative to said mounting plate, an arm supported at one end bysaid mounting plate, means securing said second electrical contact tosaid arm at a portion thereof remote from said one end, a manuallyrotatable shaft supported for rotation relative to said mounting plate,and means responsive to rotation of said shaft for moving said portionof said arm relative to said mounting plate comprising a cam 'on saidshaft and a cam follower on said arm engageable with said cam.

5. A manually adjustable indicating device comprising a setting pointerrotatable about an axis, an indicating pointer, first and second matableelectrical contacts, an

. arm supporting said second'electrical contact, means for supportingone end of said arm at a point remote from said settingpointer and fromsaid setting-pointer axis, a manually rotatable shaft, means includingsaid shaft for shifting the position of said setting pointer, meansineluding said shaft and said arm for varying the position of saidsecond electrical contact, and electroresponsive means for varying thepositions of both said indicating pointer and said first electricalcontact.

6. A manually adjustable indicating device comprising a setting pointer,an indicating pointer, first and second matable electrical contacts, anarm supporting said second electrical contact, a manually rotatableshaft, means including said shaft for shifting the position of saidsetting pointer, means including said shaft and said arm for varying theposition of said second electrical contact, an ambient temperaturecompensated polymetallic element, a heater winding in heat exchangerelation with said element for defiectingan end portion of said element,means supporting said first electrical contact on said end portion, aspring element having a hook adjacent one end, and a link engaging saidend portion and said hook and pivotal in response to movement of saidend portion about said hook, said indicating pointer being supported bysaid link.

7. A manually adjustable indicating device comprising a setting pointer,an indicating pointer, first and second matable electrical contacts, anarm supporting said second electrical contact, a manually rotatableshaft, means including said shaft for shifting the position of saidsetting pointer, means including said shaft and said arm for varying theposition of said second electrical contact, an ambient temperaturecompensated polymetallic element, a heater winding in heat exchangerelation with said element for deflecting an end portion of saidelement, means supporting said first electrical contact on said endportion, a spring element having a hook adjacent one end and spaced fromsaid shaft, and a link engaging said end portion and said hook andpivotal in response to movement of said end portion about said hook,said indicating pointer being supported by said link.

8. A manually adjustable indicating device comprising a setting pointer,an indicating pointer, first and second matable electrical contacts, anarm supporting said second electrical contact, a manually rotatableshaft, means including said shaft for shifting the position of saidsetting pointer, means including said shaft and said arm for varying theposition of said second electrical contact, an ambient temperaturecompensated polymetallic element, a heater winding in heat exchangerelation with said element for deflecting an end portion of saidelement, means supporting said first electrical contact on said endportion, a spring element having a hook adjacent one end, and a linkengaging said end portion and said hook and pivotal in response tomovement of said end portion about said hook, said indicating pointerbeing supported by said link, the pivotal axis of said link and of saidindicating pointer being spaced from said shaft.

9. A manually adjustable indicating device comprising a setting pointer,an indicating pointer, first and second matable electrical contacts, anarm supporting said second electrical contact, a manually rotatableshaft, means including said shaft for shifting the position of saidsetting pointer, means including said shaft and said arm for varying theposition of said second electrical contact, an ambient temperaturecompensated polymetallic element, a heater winding in heat exchangerelation with said element for deflecting an end portion of saidelement, means supporting said first electrical contact on said endportion, a spring element having a hook adjacent one end, and a linkengaging said end portion and said hook and pivotal in response tomovement of said end portion about said hook, said indicating pointerbeing supported by said link, the pivotal axis of said link and of sa dindicating pointer being spaced from said shaft but n substantialalignment with the rotational axis of said shaft.

10. A manually adjustable indicating device comprising a settingpointer, an indicating pointer, first and second matable electricalcontacts, an arm supporting said second electrical contact, a manuallyrotatable shaft, means including said shaft for shifting the position ofsaid setting pointer, means including driving means on said shaft anddriven means on said arm engageable with said driving means for varyingthe position of said second electrical contact, an ambient temperaturecompensated polymetallic element, a heater winding in heat exchangerelation with said element for deflecting an end portion of saidelement, means supporting said first electrical contact on said endportion, a spring element having a hook adjacent one end, and a linkengaging said end portion and said hook and pivotal in response tomovement of said end portion about said hook, said indicating pointerbeing supported by said link, the pivotal axis of said link and of saidindicating pointer being spaced from said shaft.

ll. A manually adjustable indicating device comprising a settingpointer, an indicating pointer, first and second matable electricalcontacts, an arm supporting said second electrical contact, a manuallyrotatable shaft, means including said shaft for shifting the position ofsaid setting pointer, means including a gear on said shaft and a rack onsaid arm engageable with said gear for varying the position of saidsecond electrical contact, an ambient temperature compensatedpolymetallic element, a heater winding in heat exchange relation withsaid element for deflecting an end portion of said element, meanssupporting said first electrical contact on said end portion, a springelement having a hook adjacent one end, and a link engaging said endportion and said hook and pivotal in response to movement of said endportion about said hook, said indicating pointer being supported by saidlink, the pivotal axis of said link and of said indicating pointer beingspaced from said shaft.

12. A manually adjustable indicating device comprising a settingpointer, an indicating pointer, first and second matable electricalcontacts, an arm supporting said second electrical contact, a manuallyrotatable shaft, means including said shaft for shifting the position ofsaid setting pointer, means including a cam on said shaft and a camfollower on said arm engageable with said cam for varying the positionof said second electrical contact, an ambient temperature compensatedpolymetallic element, a heater winding in heat exchange relation withsaid element for deflecting an end portion of said element, meanssupporting said first electrical contact on said end portion, a springelement having a hook adjacent one end, and a link engaging said endportion and 8 said hook and pivotal in response to movement of said endportion about said hook, said indicating pointer being supported by saidlink, the pivotal axis of said link and of said indicating pointer beingspaced from said shaft.

13. A manually adjustable indicating device comprising a settingpointer, an indicating pointer, first and second matable electricalcontacts, an arm supporting said second electrical contact, a manuallyrotatable shaft, means including said shaft for shifting the position ofsaid setting pointer, means including said shaft and said arm forvarying the position of said second electrical contact, an ambienttemperature compensated polymetallic element, means for drivinglycoupling said element to said indicating pointer, a heater winding inheat exchange relation with said element for deflecting an end portionof said element, and means supporting said first electrical contact onsaid end portion.

14. A manually adjustable indicating device comprising a mounting plate,a setting pointer, an indicating pointer, first and second matableelectrical contacts, an arm supporting said second electrical contact,means for supporting one end of said arm upon said mounting plate, amanually rotatable shaft rotatably supporting said setting pointer androtatably supported by said mounting plate at a location remote fromsaid one end of said arm, means including said shaft and said arm forvarying the position of said second electrical contact, an ambienttemperature compensated polymetallic element, means for drivinglycoupling said element to said indicating pointer, a heater winding inheat exchange relation with said element for deflecting an end portionof said element, and means supporting said first electrical contact onsaid end portion.

15. A manually adjustable device comprising a setting pointer, manuallyrotatable means for adjusting said setting pointer, an indicatingpointer, a first electrical contact, a polymetallic element carryingsaid first electrical contact, a heater winding in heat exchangerelation with said element for deflecting a portion of said element,means drivingly connecting said element to said indicating pointer, anarm supported independently of said pointers, and a second electricalcontact carried by said arm and matable with said first electricalcontact.

16. A manually adjustable device comprising a setting pointer, manuallyrotatable means for adjusting said setting pointer, an indicatingpointer, a first electrical contact, a polymetallic element carryingsaid first electrical contact, a heater winding in heat exchangerelation with said element for deflecting a portion of said element,means drivingly connecting said element to said indicating pointer, anarm supported independently of said pointers, a second electricalcontact carried by said arm and matable with said first electricalcontact, and means including said manually rotatable means and said armfor moving said second electrical contact relative to said firstelectrical contact.

References Cited in the file of this patent UNITED STATES PATENTS1,567,589 Greenawalt Dec. 29, 1925 1,673,591 Reid June 12, 19282,436,444 Merrick Feb. 24, 1948 2,780,709 Thompson et a1 Feb. 5, 1957

